// https://leetcode-cn.com/leetbook/read/top-interview-questions-easy/xnnhm6/
var reverseList = function (head) {
    let p1 = head
    let p2 = null
    while (p1) {
        const tep = p1.next
        p1.next = p2
        p2 = p1
        p1 = tep
    }
}; 